Ophthalmic pressure control system, a kit of parts and a method

ABSTRACT

The invention relates to an ophthalmic pressure control system, comprising: a pressure regulator having an input port and an output port, and an infusion line having a proximal end and a distal end, the proximal end being connected to the output port of the pressure regulator, and the distal end being detachably connected to an ophthalmic irrigation module. Further, the system includes a control unit driving the pressure regulator for controlling an infusion fluid pressure at a distal end of the ophthalmic irrigation module. The control unit is arranged for performing a fluid calibration process including a step of determining a fluid impedance of the ophthalmic irrigation module. The infusion line is associated with a kit of parts including a first and a second ophthalmic irrigation device, or the ophthalmic irrigation module is an ophthalmic irrigation device for surgical use.

RELATED APPLICATIONS

This application claims priority to and the benefit of NetherlandsApplication No. 2020558, filed on Mar. 9, 2018, entitled “An OphthalmicPressure Control System, A Kit of Parts and a Method”, and is also aContinuation Application of U.S. application Ser. No. 16/297,080,entitled “An Ophthalmic Pressure Control System, A Kit of Parts and aMethod”, filed on Mar. 8, 2019 which is incorporated herein by referencein its entirety.

SPECIFICATION

The invention relates to an ophthalmic pressure control system,comprising

a fluid pressure regulator having an input port and an output port, aninfusion line having a proximal end and a distal end, the proximal endbeing connected to the output port of the pressure regulator, and thedistal end being detachably connected to an ophthalmic irrigationmodule, and a control unit driving the pressure regulator forcontrolling an infusion fluid pressure at a distal end of the ophthalmicirrigation module.

In ophthalmic surgery, small probes are inserted into an eye, via aninsert opening e.g. a cannula through the pars plana of the eye, to cut,remove or otherwise manipulate tissue. Typically, the interior of theeye is flushed with an infusion fluid by flowing the fluid into the eyevia an ophthalmic irrigation module penetrating the eye. The irrigationmodule is fed by an infusion line that is pressurized by a fluidpressure regulator. During manipulating tissue in the interior of theeye, the amount of fluid leaving the eye via the insert opening can varyover time, e.g. depending on surgical acts.

In prior art systems, the fluid flow towards the eye may be controlledusing a control unit that drives the pressure regulator for controllingan infusion fluid pressure at a distal end of the ophthalmic irrigationmodule. The controlling process can be based on a sensed fluid pressurein the interior of the eye. As an alternative, European patent EP 2 538900 B1 in the name of the same applicant discloses that the fluidpressure is estimated without use of a fluid pressure sensor.

It is an object of the present invention to provide an ophthalmicpressure control system wherein a process of controlling an infusionfluid pressure at a distal end of the ophthalmic irrigation module isimproved. Thereto, according to the invention, the control unit isarranged for performing a fluid calibration process including a step ofdetermining a fluid impedance of the ophthalmic irrigation module,wherein either the infusion line is associated with a kit of parts,comprising a first ophthalmic irrigation device for surgical use, thekit of part further comprising a second ophthalmic irrigation device forcalibration use, such that the ophthalmic irrigation module detachablyconnected to the infusion line is the second ophthalmic irrigationdevice of the kit of parts, or wherein the ophthalmic irrigation moduleis an ophthalmic irrigation device for surgical use.

By performing a calibration process, a static and/or dynamic fluidresponse to an action of the pressure regulator can be evaluated,thereby improving the system to compensate for a pressure loss in theinterior of the eye due to surgical acts in the eye, e.g. in terms ofcompensation speed and accuracy, e.g. for setting the fluid pressure inthe eye to a pre-defined set point.

According to an aspect of the invention, an insight is exploited thatthe fluid impedance of the ophthalmic irrigation module may have asignificant contribution to the fluidal behaviour of the ophthalmicpressure control system, due to the relatively small dimensions of theirrigation module. By determining a fluid impedance of the ophthalmicirrigation module, the overall fluid response of the system can beestimated more accurately, thereby further improving the pressurecontrolling process.

By using the system according to the invention, an intraocular eyepressure can be kept stable at a value set by the surgeon, regardless ofany surgical procedure.

Further, by associating the infusion line with a kit of parts,comprising a first ophthalmic irrigation device for surgical use, thekit of parts further comprising a second ophthalmic irrigation devicefor calibration use, such that the ophthalmic irrigation moduledetachably connected to the infusion line is the second ophthalmicirrigation device of the kit of parts, the control unit can perform thefluid calibration process including the step of determining the fluidimpedance of the irrigation module without being physically connected tothe first irrigation device that is actually used in a surgery process.Then, the calibration process can be performed while the secondirrigation device for surgical use is located elsewhere, e.g. in asurgical position e.g. penetrating the eye. After the calibrationprocess has finalized, the first irrigation device for calibration usecan be replaced by the irrigation device for surgical use, while stillin the surgical position, thereby minimizing surgical acts.

Advantageously, the determined fluid impedance can be compared with amultiple number of predetermined fluid impedance calibration referencevalues associated with corresponding types of ophthalmic irrigationdevices. As the ophthalmic irrigation device that is used duringcalibration in practice belongs to a set including a limited number ofdevice types, e.g. depending on a geometry and/or size of the device,the fluid impedance determination can be used for identifying the typeof the device to be used in a surgery process, i.e. the first device.The fluid impedance calibration reference values can be measured inadvance, during laboratory conditions and/or using dedicated measuringsensors, and can be provided together with the first and second device,e.g. in a digital manner with documentation of the device. Then, anidentification of the device at hand can be obtained without a veryprecise determination of the fluid impedance. In principle, even arelatively rough, inaccurate determination of the fluid impedance of thesecond device may be useful for identifying the type of the firstdevice, especially if a comparison with the multiple number ofpredetermined fluid impedance calibration reference values can beperformed with a positive result within a high probability regime. Ifthe fluid impedance value that is determined during the calibrationprocess matches, within a chosen probability interval, with a specificreference value of the multiple number of predetermined fluid impedancecalibration reference values, a positive identification can be made withan ophthalmic irrigation device type associated with said referencevalue. Then, upon identifying the type of the first device, known fluidimpedance information of said identified first device can advantageouslybe used for evaluating a static and/or dynamic fluid response to anaction of the pressure regulator, even when a relatively global or roughdetermination of the fluid impedance is performed during the calibrationprocess.

The predetermined fluid impedance calibration reference values may matchwith the fluid impedances of the corresponding types of first ophthalmicirrigation devices. Then, the first and second ophthalmic irrigationdevice of the kit of parts have the same fluid impedance, and thematched predetermined fluid impedance calibration reference value can beused for evaluating the fluid response.

Alternatively, the predetermined fluid impedance calibration referencevalues are different from but in a unique manner related to the fluidimpedances of the corresponding types of the first ophthalmic irrigationdevices. Then, the first and second ophthalmic irrigation device of thekit of parts have a mutually different fluid impedance, however mutuallyrelated in a unique manner. The device type can be determined bydetermining the fluid impedance of the second ophthalmic irrigationdevice and relating the determined fluid impedance value of the seconddevice to the corresponding type of the first ophthalmic irrigationdevice. The step of relating the determined fluid impedance value to thetype of the corresponding first ophthalmic irrigation device can beapplied by using information of the relationship between thepredetermined fluid impedance calibration reference values on the onehand and the fluid impedances of the corresponding types of the firstophthalmic irrigation devices on the other hand. Said information can beavailable in any way, e.g. as a table.

By relating the predetermined fluid impedance calibration referencevalues in a unique manner to different fluid impedance values of thecorresponding first devices, the fluid impedance of the first and seconddevice in the kit of parts differ from each other in a unique, knownmanner. Then, the fluid impedance of the second device that is used forcalibration can be set to an impedance regime that can be measuredquickly, thereby saving calibration time. As an example, the seconddevice of a kit of parts may have a fluid impedance that is significantlower than the fluid impedance of the first device.

The first ophthalmic irrigation device may include an actuatormechanism, e.g. including a phaco needle and sleeve, while the secondophthalmic irrigation device is a passive device. However, the firstirrigation device may be identical to the second irrigation device, e.g.both devices including an actuator mechanism or both devices beingpassive, e.g. implemented as an infusion cannula.

Alternatively, the ophthalmic irrigation module that is detachablyconnected to the distal end of the infusion line, during the calibrationprocess, is an ophthalmic irrigation device for surgical use. Then, thecalibration process including the step of determining a fluid impedanceof the ophthalmic irrigation module can be performed probing a devicefor surgical use, even when the device is located in a positionpenetrating the eye.

Also in this embodiment, the determined fluid impedance can be comparedwith a multiple number of known predetermined fluid impedancecalibration reference values associated with corresponding types ofophthalmic irrigation devices, thereby relaxing accuracy requirements tothe fluid impedance determination.

In addition, the invention relates to a kit of parts.

The invention also relates to a method of controlling an infusion fluidpressure.

Further, the invention relates to a computer program product. A computerprogram product may comprise a set of computer executable instructionsstored on a data carrier, such as a CD or a DVD. The set of computerexecutable instructions, which allow a programmable computer to carryout the method as defined above, may also be available for downloadingfrom a remote server, for example via the Internet.

Further advantageous embodiments according to the invention aredescribed in the following claims.

It should be noted that the technical features described above or belowmay each on its own be embodied in a system or method, i.e. isolatedfrom the context in which it is described, separate from other features,or in combination with only a number of the other features described inthe context in which it is disclosed. Each of these features may furtherbe combined with any other feature disclosed, in any combination.

The invention will now be further elucidated on the basis of a number ofexemplary embodiments and an accompanying drawing. In the drawing:

FIG. 1 shows a schematic view of an ophthalmic pressure control systemaccording to the invention, and

FIG. 2 shows a flow chart of a method according to the invention.

It is noted that the figures show merely preferred embodiments accordingto the invention. In the figures, the same reference numbers refer toequal or corresponding parts.

FIG. 1 shows a schematic view of an ophthalmic pressure control system 1according to the invention. The system 1 includes a fluid pressureregulator 2 having an input port 3 and an output port 4. The system 1 isalso provided with an infusion line 5 having a proximal end 6 and adistal end 7, the proximal end 6 being connected to the output port 4 ofthe pressure regulator 2. In the shown embodiment, the distal end 7 ofthe infusion line 5 is detachably connected to an ophthalmic irrigationmodule 8. The infusion line 5 can be implemented as a so-called highflow infusion line. Further, the system 1 includes a control unit 9driving the pressure regulator 2 for controlling an infusion liquidpressure at a distal end 19 of the ophthalmic irrigation module 8.

During operation of the system 1, the distal end 19 of the ophthalmicirrigation module 8 penetrates into the interior of a patient's eye forflowing an irrigation fluid into said interior of the eye. By flowingirrigation fluid into the eye, any internal pressure loss in the eye,due to surgical acts in the eye, may be compensated. Upon activating thefluid pressure regulator 2, an irrigation fluid pressure is exerted, atthe distal end 19 of the ophthalmic irrigation module 8. Duringoperation of the system, the control unit 9 drives the pressureregulator 2 so as to control the infusion fluid pressure at the distalend 19 of the ophthalmic irrigation module 8.

For the purpose of regulating a fluid pressure, through the infusionline 5, the fluid pressure regulator 2 may be provided with an infusionbottle feeding the fluid pressure regulator 2 infusion line 5 via a dripchamber connected to the input port 3 of the fluid pressure regulator 2.

The control unit 9 is further arranged for performing a fluidcalibration process including a step of determining a fluid impedance ofthe ophthalmic irrigation module 8, such that the control unit maystatically and/or dynamically control the infusion fluid pressure at thedistal end 19 of the ophthalmic irrigation module 8. By characterizing afluid impedance of the ophthalmic irrigation module 8 provided with aninternal passage for flowing the irrigation fluid towards the interiorof the eye, a static and/or dynamic response of the ophthalmicirrigation module 8 can be estimated, thereby improving a fluid pressurecontrol at the distal end of the module, during surgery in the eye. Whenperforming an eye pressure compensation process, a desired fluid flowcharacteristic can be set, e.g. in terms of volume and time taking intoaccount the fluid system behaviour of the calibrated system.

In a first embodiment, shown in FIG. 1, the ophthalmic irrigation module8 is a passive device having the same fluid impedance as a correspondingophthalmic irrigation device 10 including an actuator mechanism to beused for surgical activities. The actuator mechanism may e.g. include aphaco needle and sleeve. The fluid impedance of the irrigation modulemay depend on dimensions and/or geometry of an internal fluid passagethrough the irrigation module, e.g. length, diameter, curves etc. Byusing a passive counterpart 8 of the corresponding active ophthalmicirrigation device 10, the control unit 9 can perform the fluidcalibration process including the step of determining the fluidimpedance of the ophthalmic irrigation module 8 without being physicallyconnected to the irrigation device 10 itself. The passive ophthalmicirrigation module 8 may serve as a mock module suitable for performing afluid calibration procedure.

In practice, the ophthalmic irrigation device 10, e.g. the phaco sleeve,can remain in a position penetrating the eye, e.g. traversing a cannulathat is present in the conjunctiva/sclera of the eye. Then, the passivecounterpart 8 of the active irrigation device can be detachablyconnected to the infusion line 5 for performing the calibration process,and, subsequently, the passive irrigation module 8 can be removed fromsaid infusion line 5 while the active irrigation device 10 is thendetachably connected to the infusion line 5, for operationally providingthe infusion fluid into the interior of the eye, in a controllablymanner. In other words, the passive ophthalmic irrigation module 8detachably connected to the infusion line 5 is replaced by acorresponding ophthalmic irrigation device 10 having the same fluidimpedance but including an actuator mechanism.

In FIG. 1, the passive ophthalmic irrigation module 8 is connected tothe distal end 7 of the infusion line 5, while the active irrigationdevice 10 is not connected. The passive irrigation module 8 and theactive irrigation device 10 have the same or similar fluid impedance,measured from a proximal end of the module 8, 10, thus forming a set ofrelated ophthalmic modules, or a kit of parts 11. The kit of parts 11comprises a first ophthalmic irrigation device 10 for surgical use,including an actuator mechanism, and further comprises a secondophthalmic irrigation device 8 for calibration use, implemented as apassive device having the same fluid impedance as the first ophthalmicirrigation device 10. The first ophthalmic irrigation device 10 isintended for surgical use, e.g. for placing in or on the eye, while thesecond ophthalmic irrigation device 8 serving as a dummy module 8 isintended for determining a fluid impedance of the first device 10. Thesecond ophthalmic irrigation device 8 may be implemented as a disposabletool, e.g. a dummy cannula, that can be pre-assembled on the distal end7 of the infusion line 5, as a representative tool of the actual device10. During a calibration process, a fluid resistance of the tool 8 canbe measured. Then, the tool 8 can be removed, and the infusion line 5 isin principle ready for surgical use.

A kit of parts may be provided for each gauge size of a specificophthalmic device, e.g. for each cannula gauge size. Further, the firstand second device of each kit of parts have the same or similar fluidimpedance meaning that the tolerances of the internal passage geometryof the pair of devices are with certain limits such that the estimatedintraocular pressure is with pre-specified limits.

It is noted that also the first ophthalmic irrigation device 10 can beimplemented as a passive device, without an actuator, e.g. as aninfusion cannula to be inserted into the eye. Then, the ophthalmicirrigation device used during the fluid impedance determining step canbe identical to another ophthalmic irrigation device connected to thedistal end of the infusion line after finalizing the fluid impedancedetermining step, i.e. during surgery. In this case, the kit of parts 11may include two identical ophthalmic irrigation devices, viz. a firstophthalmic irrigation device 10 that is used for performing surgicalacts, e.g. for placing in or on the eye, and a second ophthalmicirrigation device 8 that is used for determining the fluid impedance ofthe devices. It is noted that the two identical ophthalmic irrigationdevices may be both passive, i.e. without any actively driven componentor actuator mechanism, or may be both active, i.e. including an activelydriven component or actuator mechanism.

Thus, the infusion line 5 can be is associated with a kit of parts,comprising a first ophthalmic irrigation device 10 for surgical use, thekit of part further comprising a second ophthalmic irrigation device 8for calibration use, the first and the second ophthalmic irrigationdevices 10, 8 having the same fluid impedance, such that the ophthalmicirrigation module detachably connected to the infusion line 5 is thesecond ophthalmic irrigation device 8 of the kit of parts.

Advantageously, the determined fluid impedance of the second device 8 iscompared with a multiple number of predetermined fluid impedancecalibration reference values reflecting the fluid impedances of thesecond devices and associated with corresponding types of firstophthalmic irrigation devices 10. If a predetermined fluid impedancecalibration reference value can be found that is the same as thedetermined fluid impedance of the second device 8, within pre-specifiedlimits, the type of the first device 10 is identified and saidpredetermined fluid impedance calibration reference value can be usedfor evaluating a static and/or dynamic fluid response to an action ofthe pressure regulator, even when a relatively global or roughdetermination of the fluid impedance is performed during the calibrationprocess.

Alternatively, the predetermined fluid impedance calibration referencevalues, reflecting the fluid impedances of the second devices 8, aredifferent from the fluid impedances of the corresponding types of thefirst ophthalmic irrigation devices 10, however being in a unique mannerrelated to said types of the first devices 10. Again, the device typecan be determined by determining the fluid impedance of the secondophthalmic device 8 and relating the determined fluid impedance value tothe corresponding type of the first ophthalmic device, using informationof the above-mentioned unique relationship that is available in someway, e.g. using a table or algorithm. As an example, the fluid impedancevalue of the second device 8 is at least an order lower than the fluidimpedance value of the first device 10 saving calibration time if thefirst device impedance is relatively high.

It is noted that, as a further alternative, the determined fluidimpedance of the second device 8 is not compared to predeterminedreference values. Then, the determined fluid impedance itself can beused for evaluating a static and/or dynamic fluid response to an actionof the pressure regulator.

In a second embodiment, the ophthalmic irrigation module detachablyconnected to the distal end of the infusion line is an ophthalmicirrigation device 10 for surgical use, optionally located in a positionpenetrating the eye. The device 10 may include an actuator mechanism.Then, the calibration process including the step of determining a fluidimpedance of the ophthalmic irrigation module can be performed with thedevice 10 for surgical use, even when the device 10 is located in aposition penetrating the eye.

Again, the determined fluid impedance of the device 10 can be comparedwith a multiple number of predetermined fluid impedance calibrationreference values reflecting the fluid impedances of the devices, for thepurpose of identifying the type of device at hand.

FIG. 2 shows a flow chart of a method according to the invention. Themethod is used for controlling an infusion liquid pressure at a distalend of an ophthalmic irrigation module. The method 100 comprises a stepof providing 110 a fluid pressure regulator having an input port and anoutput port, a step of providing 120 an infusion line having a proximalend and a distal end, the proximal end being connected to the outputport of the pressure regulator, a step of detachably connecting 130 thedistal end of the infusion line to an ophthalmic irrigation module, astep of providing 140 a control unit driving the fluid pressureregulator for controlling an infusion fluid pressure at a distal end ofthe ophthalmic irrigation module, and a step of performing 150 a fluidcalibration process including a step of determining a fluid impedance ofthe ophthalmic irrigation module, wherein the infusion line isassociated with a kit of parts, comprising a first ophthalmic irrigationdevice for surgical use, the kit of part further comprising a secondophthalmic irrigation device for calibration use, the first and thesecond ophthalmic irrigation devices having the same fluid impedance,such that the ophthalmic irrigation module detachably connected to theinfusion line is the second ophthalmic irrigation device of the kit ofparts,

or wherein the ophthalmic irrigation module is an ophthalmic irrigationdevice for surgical use.

The method may further comprise a step of disconnecting the secondophthalmic irrigation device. Then, the second ophthalmic irrigationdevice can be replaced by the first ophthalmic irrigation device.

The step of performing a fluid calibration process including a step ofdetermining a fluid impedance of the ophthalmic irrigation module can beperformed using dedicated hardware structures, such as FPGA and/or ASICcomponents. Otherwise, the method can at least partially be performedusing a computer program product comprising instructions for causing aprocessor of a computer system to perform the above described step. Anumber of steps can in principle be performed on a single processor.However it is noted that at least one step can be performed on aseparate processor, e.g. the step of determining a fluid impedance ofthe ophthalmic irrigation module.

The invention is not restricted to the embodiments described herein. Itwill be understood that many variants are possible.

These and other embodiments will be apparent for the person skilled inthe art and are considered to fall within the scope of the invention asdefined in the following claims. For the purpose of clarity and aconcise description features are described herein as part of the same orseparate embodiments. However, it will be appreciated that the scope ofthe invention may include embodiments having combinations of all or someof the features described.

1. An ophthalmic pressure control system, comprising: a fluid pressureregulator having an input port and an output port; an infusion linehaving a proximal end and a distal end, the proximal end being connectedto the output port of the pressure regulator, and the distal end beingdetachably connected to an ophthalmic irrigation module, and a controlunit driving the pressure regulator for controlling an infusion fluidpressure at a distal end of the ophthalmic irrigation module, whereinthe control unit is arranged for performing a fluid calibration processincluding a step of determining a fluid impedance of the ophthalmicirrigation module, and wherein the ophthalmic irrigation module is anophthalmic irrigation device for surgical use.
 2. A method ofcontrolling an infusion liquid pressure at a distal end of an ophthalmicirrigation module, comprising the steps of: providing a fluid pressureregulator having an input port and an output port; providing an infusionline having a proximal end and a distal end, the proximal end beingconnected to the output port of the pressure regulator; detachablyconnecting the distal end of the infusion line to an ophthalmicirrigation module; providing a control unit driving the fluid pressureregulator for controlling an infusion fluid pressure at a distal end ofthe ophthalmic irrigation module, and performing a fluid calibrationprocess including a step of determining a fluid impedance of theophthalmic irrigation module, wherein the ophthalmic irrigation moduleis an ophthalmic irrigation device for surgical use.
 3. The methodaccording to claim 2, further comprising a step of comparing thedetermined fluid impedance with a multiple number of predetermined fluidimpedance calibration reference values associated with correspondingtypes of ophthalmic irrigation devices for surgical use.
 4. The methodaccording to claim 3, wherein the predetermined fluid impedancecalibration reference values match with the fluid impedances of thecorresponding types of ophthalmic irrigation devices for surgical use.5. The method according to claim 3, wherein the predetermined fluidimpedance reference values are different from but in a unique mannerrelated to the fluid impedances of the corresponding types of ophthalmicirrigation devices for surgical use.
 7. A computer program product forcontrolling an infusion fluid pressure at a distal end of an ophthalmicirrigation module, the module being detachably connected to a distal endof an infusion line having a proximal end connected to an output port ofa pressure regulator, the computer program product comprising computerreadable code for causing a processor to perform a step of performing afluid calibration process including a step of determining a fluidimpedance of the ophthalmic irrigation module, wherein the ophthalmicirrigation module is an ophthalmic irrigation device for surgical use.